Those of you who have Smooth Scrolling and Zooming problem on ALL LOGITECH MOUSE, here is a fix!!!
SOFTWARE ENGINEERS please fix this issue, rather than telling people to uninstall Logitech Setpoint Plugin on Chrome and on other browser.This guide will turn off CTRL+Mouse Scroll, smooth scroll is in effect, you can still zoom in and out by using CTRL +/-. and still enjoy smooth scrolling. I use this for my M705 Marathon Mouse because it also has Smooth Scrolling Physical Mouse Scroll. (no more redness on my index finger)

1. download Autohotkey, then install it off course. (take note of where you install it)
2. launch it.
3. after launching it you will see the small "H"(autohotkey icon on the lower right of your monitor beside the clock) and "rightclick on it" then choose "edit this script".
4.A notepad will pop-up then add the script below at he BOTTOM of the notepad.

Now we have to make autohotkey launch automatically when windows 8 boots up.
6. Make a shortcut of the "autohotkey.exe" go to the folder where you installed it then
"right click>send to>desktop create a shortcut"
7. Go to the desktop then right click on the shortcut then choose "cut".
8. Now open windows explorer by pressing "Windows key + E" at the same time.
9. Copy and Paste this:

C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup

on the "Explorer address bar". then press ENTER.
10. Right click on the folder and "paste". Close the Windows Explorer Folder< then restart.

This autohotkey is a small software will not slow down your PC and it is an Open Source software and free.
and it has no virus not spayware, if you don't know autohotkey, may be you came from the moon.
here is the link (edit out third party link)

Please Logitech look into this PROBLEM so we customers and you as a company will benefit from it in the long run. Fix this already.